I don’t know your ionic version, but now you can add an ionic navigation title without having to override it using the ionic navigation button, as you did. It is cleaner and works better. Alternatively, to make sure your title is centered, you can add "align-title: center" in the definition of your ion navigator. Here is an example:
<ion-nav-bar class="bar bar-header bar-assertive" align-title="center">
<ion-nav-back-button>
</ion-nav-back-button>
<ion-nav-title>
<img alt="Company Logo" height="40" src="img/logo.png">
</ion-nav-title>
<ion-nav-buttons side="right">
<button class="button button-icon button-clear ion-navicon" menu-toggle="right">
</button>
</ion-nav-buttons>
</ion-nav-bar>
Here you have the codepen link: http://codepen.io/anon/pen/RWLyMW